Single-walled and double-walled carbon nanotubes (SWNTs and DWNTs, respectively) possess excellent electronic and thermal transport properties while offering high strength. As such, they have been identified as excellent candidates for applications including electronics, thermal management, radiation sources, and biological sensors. SWNTs and DWNTs have commercial potential in electron emitters for flat panel displays, gas and biological sensors, metallic electrical interconnects, and semiconducting channels for field effect transistors. While “proof of concept” experiments and prototypes have verified the performance of SWNTs in these applications, full utilization of their potential has been hindered by the lack of a reliable platform upon which to manufacture devices and a lack of synthesis control. Many prototype devices (such as field effect transistors) rely on dispensing CNTs in solution upon functionalized substrates to bridge one or more CNTs across electrical contacts. Other applications, such as electron emission devices and electrical interconnects, often rely on largely uncontrolled growth of dense CNTs mats.
Carbon nanotubes (CNTs), first discovered in 1991 by Sumio lijima, have become the subject of intense scrutiny from many scientific and engineering disciplines. CNTs are cylindrical carbon molecules composed of one or more conjoined graphitic layers (called graphene sheets). CNTs having only one graphene shell are called single-walled carbon nanotubes (SWNTs), while those having multiple concentric shells are called multi-walled carbon nanotubes (MWNTs). SWNTs have a typical diameter ranging from 1-3 nm, while MWNTs may have diameters of up to tens of nanometers. One type of MWNT is double-walled CNTs (DWNTs), as they typically have dimensions, physical properties and electrical properties similar to those of SWNTs.